I am my own worst critic when it comes to my body. I've wasted years conducting daily appraisals in the mirror and cruelly judging my trouble areas. ("You could rest a teacup on that stomach roll!") I'd always hoped that getting older would somehow magically silence those nasty inner voices, but I recently turned 40 and, thus far, age has failed to bring about a Zen state of body acceptance.

So when a photographer friend mentioned that a colleague of hers was working on a series of nude portraits of women over 40, I knew what I had to do: Pose in the altogether. Confront reality. Lay myself bare. I listed the pros in my head: (1) I'd be forced to face my fears. (2) I'd be extra motivated to work out and eat well leading up to the shoot. (3) Because I was still on the outer edge of youthful, I could do this now—or never. (4) It would be an adventure. The only two reasons I could think of for not going through with it were that the photos could be hideous, which would simply serve to increase the volume of my mirror critiques, and that I would have to expose myself, literally and figuratively. It was a risk, but one I decided I was willing to take.

I had to psych myself up for months before calling the photographer, a woman named Koren Reyes. When I finally did, she said, "Women over 40 don't get as much appreciation as they should. Female bodies of all ages and sizes are beautiful."

"I worked with someone who was well over 200 pounds. And the pictures were great," she said. Beyond that, Koren refused to promise me everlasting serenity or to vanquish my demons, though she was willing to say that everyone she'd worked with had had a positive experience. I almost asked for that promise in writing. We set a date for six weeks hence.

When I told folks about my plan, they called me either crazy or brave, both of which I took to be mildly insulting. But mostly, I tried not to think about the upcoming project much, other than as a lark. Then, a week before the shoot, Koren e-mailed me: She'd rented a studio and hired a makeup artist and assistant. I gulped, horrified that other people would be there, watching the process. Weird concerns ran through my head. What if I suddenly got my period? What if I broke out with bacne?

To combat my fears, I did my very best to make myself presentable the day before the event. I depilated my legs, arms, belly, chin, upper lip, eyebrows and armpits. Should anyone get the urge to examine the photographs under a magnifying glass, they would not find a single unwanted hair. I removed all toe and fingernail polish (I was going for a natural look). I exfoliated and moisturized myself. Twice.

Smooth and glowing, I arrived at the studio at 9 A.M., sans breakfast, which I hoped would make me appear 10 pounds slimmer. The assistant, Maggie, a photographer herself, told me she'd posed nude a few times—"topless and full body"—as if it were nothing at all. Yuko, the rail-thin hair-and-makeup artist, was soft-spoken and sweet and promised to work wonders on me, from the neck up, at least. Koren herself was also trim and stylish, exuding an air of professional competence. As we talked about possible poses, I tried to seem cool and confident, ever eager to impress, but inside my stomach was churning.

When Yuko was done with my makeup, I dashed into the bathroom, stripped, checked myself out in the mirror one last time and donned a bathrobe. Then I walked out into the studio, a cavernous space with umbrella lights. An enormous roll of white paper, known as a seamless, was pulled down one wall and across the bare floor. Though the room was cold, I immediately started to sweat. Koren, camera in hand, asked me to stand on the seamless. Maggie tested the lighting. And then Koren directed me to lose the bathrobe.

This was virgin territory. I love locker rooms—they showcase the diversity of the female form—but I don't linger in them. I'd never been fully, flagrantly nude for more than five minutes before other women. Now I was starkers in front of three—and would be for several hours.

I took a deep breath, paused and shrugged off my robe. I wasn't expecting applause but something other than dead silence would have been nice. When I've gotten naked for men in the past, especially for the first time, most invariably say something complimentary, even if out of sheer politeness. These women, on the other hand, stared, or rather, studied my nudity as if I were a specimen. I nearly said, "Hello! Naked person here! A kind word needed!"

Finally, Koren spoke: "OK, sit down facing me, cross your legs at the ankle and fold your arms over your knees." And just like my clothes, we were off.

The lack of flattery bothered me, and as I arranged myself into position, I twisted internally, too. Then again, convincing me of my own attractiveness was not Koren's job. It was mine, one I'd failed at chronically. Was my ego so weak that I couldn't survive without the benefit of idle puffery?

By concentrating on Koren's directions ("Drop the shoulders," "Keep your chin down"), I was able (mostly) to get over myself. And the more I relaxed, the more Koren demanded of me. She never had me expose too much skin (my private parts, for instance, were always hidden). Her goals were to help me feel comfortable and take the best shots possible. At one point, to loosen me up, she instructed, "Act like you've been caught coming out of the shower!" Later, she coaxed me to go for a more sultry demeanor, demanding, "Pout for me." I must have looked like a deranged porn star on that one, because Koren quickly said, "On second thought, don't pout. Ever." That made me laugh hard, resulting, as I later learned, in some of my brightest smiles and the best photographs of the day.

Because we were all working toward a common goal—pretty pictures—my nudity started to feel productive and purposeful as opposed to gratuitous. And despite the fact that I was naked, the atmosphere was also decidedly nonsexual. I was reminded of my one experience on a nude beach in Martha's Vineyard and how my bareness had felt free, natural, fun. Only occasionally did I pause to think, I can't believe I'm flat on my back with my breasts hanging out for everyone to see.

As the day progressed, I even began to believe that I could achieve pulchritude. For one pose, Yuko arranged my hair so the curls draped suggestively over my shoulder. When I rested my cheek on my knee, the strands swept my bare skin and it felt good; without thinking about it, I smiled dreamily. Maggie said an emphatic, "Nice!" and I experienced a veritable I-feel-pretty moment. I compared that with my daily scrutiny in the mirror, how I inevitably zeroed in on the ugly. Next time, I vowed, I would look at myself with a more generous, artistic eye.

The shoot lasted until lunch, when, relieved to finally be dressed again, I scarfed down my sandwich. Koren asked what I'd thought of the experience, and I admitted that I'd been tense at first, transferring my own harsh self-judgments to Koren and her crew. "But after 10 minutes," I said, "I saw the humor in it. How could rolling around on the floor in the buff be anything but funny?"

Unless, that is, the pictures ended up being awful; then the whole enterprise would be tragic. I couldn't tell much from the tiny postage-stamp images Koren showed me on her digital camera, but the photos she sent the next day were a revelation. Granted, in some shots, my belly looked like a deflated beach ball and my boobs like pancakes, but most of the images were quite presentable. In about half of them, I looked downright cute. In a dozen, I would call myself hot. Not thin. Never that. But it struck me then that thin does not necessarily equal hot. Hot does not necessarily equal thin. The range of thin is narrow. The universe of hot is vast and ever-expanding.

My husband loved the pictures. "Most models look pissed off or mean," he said. "You look sexy in a completely nonthreatening way. You look like you had a good time." I realized I had. A great time, actually.

I pored over the photos for days, discounting the deflated beach ball and pancake shots as bad angles. With so many better angles to choose from, the unflattering ones hardly mattered. I was—I am—learning to edit, both my photo portfolio and my critical thoughts. When my husband suggested we frame some for the posterity of my posterior, I chose a spot next to my bedroom mirror as a visual rebuttal to my inner harridan should she dare to speak up.

Except lately my critical chatter has been barely audible. The photos have helped turn me away from the negative and toward the positive. These days, instead of fixating on my flabby gut in the mirror, my eyes go to my strong legs, sleek shoulders and pretty face. Of course, these were right before my eyes all along, beauty hiding in plain sight. Only now, I can finally see it.